Electrical contacting arrangement

ABSTRACT

A composite electrical contact structure which includes a laminate of an aluminum layer bonded to a layer of high-grade contact material such as copper or silver onto the aluminum layer of which is then cast a base body of aluminum or aluminum alloy. During casting of the base body, the surface of the aluminum layer is fused by and becomes united with the molten aluminum upon solidification of the latter.

United States Patent Mosele [4 1 Apr. 1%, H972 [54] ELECTRICALCONTACTING References Cit ARRANGEMENT UNITED STATES PATENTS Inventor:Joset Mosele, Obere Brucke, Othmarsin- 3,198,662 8/1965 Seibert..200/166 0 ux gen, Switzerland 3,299,240 1/1967 Foti ..200/l66 C Mar etal C [21] Appl. No.: 18,085 Primary Examiner-41. 0. JonesAttorney-Pierce, Scheffler & Parker [30] Foreign Application PriorityData 57 ABSTRACT P 1,1969 Switzerland -4943/69 A composite electricalcontact structure which includes a laminate of an aluminum layer bondedto a layer of high-grade [52] US. Cl. ..200/166 C, 29/630 C contactmaterial such as copper or silver onto the aluminum [51] Int. Cl. ..H01h1/02 layer of which is then cast a base body of aluminum or alu- [58]Field of Search ..200/166 C; 29/630 C m n alloy. ng ng o the e o y, thesurface of the aluminum layer is fused by and becomes united with themolten aluminum upon solidification of the latter.

2 Claims, 1 Drawing Figure PATENT EDAPR 18 1972 3, 657', 505

Fig.2

INVENTOR. Jose I MoseLe BY At me s 1 ELECTRICAL CONTACTING ARRANGEMENTThe present invention relates to an electrical contact arrangement,especially for power circuit breaker apparatus, in which a base body ofaluminum or aluminum alloy is joined to a contact piece of high-gradecontact material by casting.

In bodies of aluminum or aluminum alloy which serve for the conductionof current and the transmission of current to other parts, the pointwhere contact is made has received particular attention for a long time.A satisfactory solution, however, has not yet been found to date. Thus,contact pieces of high-grade contact material, for instance, copper orsilver, have been applied to an aluminum base body in various ways.Besides bolting on of copper parts, it is known among other things howto fasten sheet silver to the aluminum base body by means of spotwelding for the purpose of providing contact. It is true that with thisletter method a usable contact point is obtained at the silver-aluminumtransition, but the contact areas outside the welding points are poorlyutilized with regard to current and heat transfer. It is also known tojoin current transfer contacts of high-grade contact material, forinstance, copper, to the aluminum body by casting, wherein the aluminumis cast onto the copper parts as a die casting, or the latter are castinto the former. Here, however, a more or less imperfect transitionresistance cannot be avoided, as no intimate, continuous bond betweenthe aluminum body and the contact material comes about. The presentinvention is based on the task to find a solution for applying contactsto a base body of aluminum or aluminum alloy with a high-grade material,in which the contact transition is substantially improved over thearrangements so far proposed, with respect to from the electrical aswell as thermal aspects. in accordance with the invention it is proposedthat the contact piece-be a composite body consisting of aluminum andthe high-grade contact material, the aluminum side of which faces thebase body. In this manner there is obtained between the base body andthe aluminum side of the composite body an intimate, homogeneousmetallic bond which remains free of corrosion and in which the entirecross section of the transfer area is utilized.

The accompanying drawings show two examples of implementation of theinvention.

FIG. 1 is a half longitudinal section showing the point of contactbetween two tubular conductors, and

FIG. 2 is a similar sectional view showing a sliding contactarrangement.

In FIG. 1 the two tubular conductors l and 2 are arranged so that theybutt against each other with their end faces. The conductors 1, 2consist of aluminum or aluminum alloy and each have at the end face thecontact bodies 3 and 4, respectively, each of which, as.a compositebody, consists of two layers 3a, 3b and 4a, 411, respectively. Thelayers 3a and 4a, respectively, consist of aluminum and the layers 3b,4b respectively consist of high-grade contact material, such asfor-example, copper or silver. Such composite bodies are manufactured byrolling together under pressure and heat to form a laminate and arecommercially available in various forms, for instance, in plate form,for instance, as the so-called Cupal plate. Thicknesses from 0.5 to 8 mmwith different layer thickness ratios of Al to Cu or Ag, respectively,are common. The tubular conductor part 1 can for example, be cast froman ingot of aluminum alloy, wherein the laminated body 3 is placed intothe casting mold prior to pouring the molten aluminum into the mold, insuch a manner that the aluminum side, layer 3a, faces the casting zonefor the conductor body 1 as the latter is cast. It is of advantage touse technically pure aluminum (99.5 percent) for the composite bodysince this avoids destruction of the bond between the layers 3a, 3b ofthe composite body 3 during the casting and fusion of the aluminum layer30 as the latter is joined to the adjacent surface of the aluminumconductor body during its solidification following pouring, andpossibly, the refining process, since in this case the processingtemperature is sufficiently below the melting temperature of theeutectic of the transition alloy Cu or Ag, respectively, against thepure aluminum inthe composite body.

At the inside and outside diameters, the composite bodies 3, 4 and anadjacent portion of the conductor 1, 2 can be covered with a suitableprotective lacquer, so that access of air and moisture to the contactpoint is prevented. The required contact pressure between the conductorsl and 2 can be achieved, for example, by pressing them together in amanner known per se, not shown in detail. If the contacting layers 3b,4b consists, for example, of copper, they can be silver-plated afterthey have been faced off to make them flat.

In FIG. 2 the ring shaped composite body 8, built up from the aluminumand copper layers 8a, 8b, is cast into the outer surface of the tubularshaped aluminum base body 5. On the side of the outer layer ofhigh-grade contact material 8b rest the contact fingers 9. There areseveral of these fingers 9, distributed around the circumference. Theycan consist, for example, of silver-plated copper and are held in afixed cage 10, with the insertion of the contact pressure springs 11.Within the part 5 is accommodated, by means of an insulating plasticring 7, a nozzle switch piece 6 which is supported and driven so that itcan reciprocate in the direction of the double-headed arrow 12. Theswitch piece 6 consists, for example, of silverplated copper and theright-hand ends of the fingers 6 slide on it. The two end faces of thesheet-shaped composite body 8 each can terminate in a small recess inthe shape of an annular groove in the base body 5, so that they do nottouch the latter. The groove can be filled with a protective lacquerwhich possibly also covers the bodies 5, 8 to some extent.

I claim:

1. A composite contact structure comprising a laminate consisting of analuminum layer bonded to a layer of highgrade contact material and abase body essentially of aluminum cast upon and fused with said aluminumlayer.

2. An electrical contact structure as defined in claim 1 wherein saidaluminum layer consists of technically pure (99.5 percent) aluminum.

mm m. 3, 57,505 Dated April 1 1972 Inventor (X) MOSELE JOSEF I: isccrtificd that error appears in the and ch-1'7; uaid Letters Patent a.

rc hereby corrected as shown below:

' In the-fheaqlng of the ,patent the identity of the a sl n eg ."to wit:.AKTIENGESELLSCHAFT v BROWN, 'BOVERI & 'cIE.', BA'DEN, SWITZERLAND,should appear.

-S ignedand se aled, this 10th day of October 197;.

(SEAL) Attest: v EDWARD MQFLE'TCHIERQJ'RD W ROBERT GOTTSCHALK Attesting'Officer- Commissioner of Patents

2. An electrical contact structure as defined in claim 1 wherein saidaluminum layer consists of technically pure (99.5 percent) aluminum.